1. Field of the Invention
The present invention relates, generally, to an input device for electronic equipment and, more particularly, to an input device connectable with data processors for a hand-held operation.
2. Description of the Related Art
Conventional input devices, connectable for use with digital data processors, such as personal computers, work stations, etc., are known to be operable in various modes. For example, a small-sized input device, generally referred to as a mouse, for enabling an operator to manually enter analogue-mode information so as to direct coordinate data, such as cursor shifting data, on a display screen is known to be simply operable by one hand of the operator. In particular, it is desired for this type of input device to have improved operability, in an ergonomic sense, so as to be comfortably operable by any operator irrespective of attributes such as age or gender.
From this viewpoint, it has been provided, in the above-described small-sized input device, that a body or housing of the input device is formed with a graspable or palm-rest section, on which an operator puts his hand, capable of enlarging and reducing the dimensions of the palm-rest section as the occasion demands. Conventionally, the enlarging/reducing (or alterable dimension) function of the palm-rest section of the input device housing has been embodied by a provision of separate grip parts having various dimensions and adapted to be attached to the palm-rest section in an exchangeable manner, or by a provision of a vertically liftable structure for the palm-rest section. That is, the conventional input device having an extendible body is generally provided with a housing capable of enlarging and reducing the dimensions thereof mainly in a height direction in accordance with an operator's requirement. Also, another type of input device with an extendible body has been suggested, wherein a housing is provided with an expandable air bag and the dimensions of a palm-rest section are variable by expanding or shrinking the air bag (see, e.g., Japanese Unexamined Patent Publication (Kokai) No. 10-307679).
In the conventional small-sized input device with the above-described extendible palm-rest section, which is provided with the housing capable of enlarging and reducing the dimensions thereof mainly in the height direction, the position or level of the hand of the operator, used for a data entering operation, is changed from a customary remembered position or level, due to the enlargement or reduction in the dimensions of the palm-rest section. Consequently, there is concern that a sense of incongruity is caused in the data entering operation or stable operability is deteriorated. Also, in the case of using the exchangeable grip parts, problems arise wherein the inventory management of the grip parts as well as the exchanging work of the latter are troublesome and also the attached grip part may be detached from the housing during the data entering operation. Further, in the extendible structure using the air bag, it is possible that the air bag is inadvertently or unexpectedly punctured, which results in a malfunction of the extendible feature of the housing.
On the other hand, it is known, in a small sized input device (or a mouse), that a third entering mechanism is provided for an image shifting or scrolling operation on a display screen, in addition to inherent first and second entering mechanisms, that is, a motion detecting mechanism for a coordinate data directing operation and a switch mechanism for a push-button or click operation. The conventional third entering mechanism includes an operating member having a rotation shaft, a rotation detecting section for detecting a rotation of the rotating shaft, and a resisting section for temporarily changing a drag force against a rotary action of the operating member at certain rotation angles to cause “chattering” which can be felt by a fingertip. The third entering mechanism may be provided further with a switching unit adapted to be actuated in accordance with the press-down operation of the operating member.
In the conventional small-sized input device with the above-described third entering mechanism, there is concern that the resisting section generates noise due to the structural feature thereof to impart chattering to the rotary action of the operating member and thereby the data entering operability is deteriorated. Also, in the case of arranging the switching unit in the third entering mechanism, wherein the switching unit is pushed by the rotation shaft of the operating member when the latter is pressed down, it is possible that the rotation shaft is unexpectedly rotated or slips and thereby the switching or pushing operation for actuating the switching unit becomes unstable.